Ask HN: How to monitor user based usage of a service

Hi all,

In our system we have to monior and track the number of calls to our API that each user does overtime. Alrought we are fine with the sum of the last ~30 days for billing purposes (thus I could use a redis system with TTL) i would also like to plot the chart of calls overtime, at least for the last day to have monitor insights.

So far we have a system that sends data to `statsd` and then to `graphite`, it works, but it's not easy to port to the other servers, and it requires quite a server to handle all the series (each user has calls, errors and other data), thus it's roughly `n-of-users * 7`. I was thinking of migrating stats to prometheus, but it does no works well with having so many time series (according to their documentation, which is actually written at the end :( https://prometheus.io/docs/practices/naming/ )

I was thinking of logging (ELK/graylog) each call and then run a query over elastic, but it seems a bit of work and it does not seem to be so simple to plot the charts.\

any idea or system to use?